1. Field of the Invention
This application relates to a self sealing cannula adapted for use in conjunction with insufflatory surgical techniques wherein a body cavity is filled with pressurized gas to maintain the cavity under a certain predetermined pressure. When the presently disclosed cannula is utilized, the proper pressure is automatically maintained within the cavity without requiring the surgeon to manually adjust or regulate any valve whatsoever.
2. Background of the Invention
Numerous surgical instruments have included sealing means to prevent the flow of fluids to or from the patient's body. For instance, U.S. Pat. No. 3,970,089 discloses a seal device for a catheter comprising an elastomeric member having a lumen through which the catheter is passed. By distending the elastomeric member to constrict the lumen, a seal against egress of blood along the interface between the catheter and the innermost surface of the member is effected.
However, of primary interest to the present invention are those cannula assemblies that are designed to maintain gas pressure within the body. Such an apparatus is disclosed in U.S. Pat. No. 3,994,287 (Turp, et al). Gas pressure within the body cavity is maintained by the use of a flexible ring with an aperture therein that is positioned within an annular valve seat portion of the cannula. A collar is placed over the flexible ring to seal the valve seat sidewalls. However, sealing is realized only when a portion of a surgical instrument is disposed within the cannula passage. Accordingly, when the surgeon removes the instrument from the passage, the seal is lost, and other means must be employed to maintain suitable gas pressure within the body cavity.
U.S. Pat. No. 3,989,049 (Yoon) discloses, inter alia, another cannula (FIG. 6) provided with a trumpet valve to maintain the desired pressure within the anatomical cavity. However, the trumpet valve must be manually regulated with a rather cumbersome procedure. The surgeon must adjust the valve, remove the trocar from the cannula, and replace it with another instrument, for instance, a laparoscope or elastic ring applicator.
Accordingly, it is an object of the present invention to provide a cannula which is self-sealing and is ideally adapted for use in insufflatory surgical procedures.
Further, it is a more specific object to provide a cannula having positive sealing even after the surgical instrument has been removed from the cannula passage.
It is an even more specific object to provide a cannula that automatically seals without requiring manipulation of any valve, so that the surgeon's hands may remain free for other purposes.
Other objects and advantages of this invention will appear in further detail hereinafter.